Method and apparatus for displaying information on the screen of a monitor

ABSTRACT

A method and apparatus for displaying information on the screen of a monitor which permits the simultaneous display of a first character and a second character in a single raster location on the screen of a monitor, and hence the overstriking or modifying of a first character with a second character in a single raster location on the monitor. In one form of the invention which involves a field sequential operation, a character generator will permit the alternate display of information from two separate memories in a single raster location by super-imposition of the characters in the raster location on the monitor. In another form of the present invention, involving line-sequential operation, a pair of character generators are employed and each operate in conjunction with each of a pair of memories and the characters thus generated in each character generator is combined in a mixer and displayed in the superimposed fashion on the screen of a monitor.

United States Patent 191 Carey et a1.

[ METHOD AND APPARATUS FOR DISPLAYING INFORMATION ON THE SCREEN OF A MONITOR [75] Inventors: Peter Maiendie Carey, Beaconsfield;

Courtney Lai-Hing, Pointe Claire, Quebec, both of Canada [73] Assignee: Lektromedia Ltd., Pointe Claire,

Quebec, Canada [22] Filed: June 14, 1973 [21] Appl. No.: 369,872

[52] US. Cl...... 340/324 AD, l78/7.5 D, 340/1725 [51] Int. Cl. G06f 3/14 [58] Field of Search 340/324 A, 324 AD;

[56] References Cited UNITED STATES PATENTS 3,479,454 11/1969 Wolff l78/6.8

3,537,096 10/1970 Hatfield 340/324 AD 3,562,415 2/1971 Michels et a1. 178/68 X 3,609,743 9/1971 Las'off et al. 340/324 AD 3,696,387 10/1972 Nussbaum 340/324 AD 7 16 51/50 Logic I 10 5.5. Logic 1 Memoryl I bit 8 O Doro C I E ontro I 20 I2 L Memory 2 an 8 =1 June 28, 1974 3,750,135 7/1973 Carey et a1 340/324 AD Primary Examiner-David L. Trafton Attorney, Agent, or Firm-Robert J. Schaap [57] ABSTRACT ter generator will permit the alternate display of information from two separate memories in a single raster location by super-imposition of the characters in the raster location on the monitor. In another form of the present invention, involving line-sequential operation, a pair of character generators are employed and each operate in conjunction with each of a pair of memories and the characters thus generated in each charac-' ter generator is combined in a mixer and displayed in the superimposed fashion on the screen of a monitor. I

30 Claims, 6 Drawing Figures Field 1 Memory 1 Field 2 Memory 2 26 Monitor Choroc ter Select 0 or Generator FATENTEDJUH 28 I974 SHEET 2 BF 3 v mEDOE M ED OE METHOD AND APPARATUS FOR DISPLAYING INFORMATION ON THE SCREEN OF A MONITOR BACKGROUND OF THE INVENTION This invention relates in general to certain new and useful improvements in character generation for display on the screen of a monitor, and more particularly, to a method and apparatus for displaying a plurality of character elements in a single raster location on the screen of a monitor.

In recent years, various systems relating to the generation of both graphical and alpha-numeric information through interactive computer terminals and other external sources, has been receiving increased prominence. Generally, these systems include an information entry device such as a manually operated keyboard entry which is capable of generating alpha-numeric information and/or graphical information. This information is then suitably processed and displayed on the screen of a monitor through an electron beam. These display systems are also quite effective and have found widespread use in a wide variety of applications including for example, the solving of pictorial. problems such as highway planning, topographical mapping and other problems which are readily solved through visual examination of physical phenomena.

These types of display have often been found to be highly effective in gaining insight into complex natural or mathematical phenomena through simulation of various types of physical situations in which a computer may or may not be involved, but which permits display devices to present the results of a simulation. In some cases, these visual display systems are used for educational purposes such as in the training of pilots, displaying of lecture materials and the like.

In many systems, the information which is displayed on the screen of the monitor is introduced directly from a keyboard or other form of entry device on a real-time basis. However, it is oftentimes difficult for the operator of the system to generate the proper type of character for a display. Usually, the keyboard which is provided with a display system will contain standard key format such as the alpha-numeric characters, andperhaps some form of graphical character. In these arrangements, each character can be displayed at one or more raster locations. Further, in some systems each character which may be comprised of a series of character generating elements, such as for example, bars or dots, or the like, will occupy a single raster location and each of the characters which are generated by these characters elements will occupy a font on the screen of the monitor.

Inasmuch as the memory devices which are operable with these display systems only provide one memory location corresponding to each character position, or to each character element position, it is not possible to include two or more character elements in any raster location. Thus, if the operator of the system erred in generating a particular character, it would be necessary to back-space on the keyboard in order to return to the character position and hence memory location in which the error was made for generating a new and correct character. In this case, the entry of the second character will automatically erase and thereby replace the first character.

LII

There is presently no system which effectively permits the superimposition of two or more characters or character elements in a single raster location on the screen of a monitor, using T.V. raster method of character generation. And this type of character superimposition is highly desirable in that it enables the operator of the system to generate essentially any form of desired graphical character. In like manner, this type of superimposition would be highly advantageous in that it would permit the operator of the system to introduce accent marks or other forms of modifying marks along with a character, such as for example an arabic character, in a single raster location on the screen of the monitor.

It is therefore the primary object of the present invention to provide a system for generating a display of characters on the screen of a monitor and for modifying these characters.

It is another object of the present invention to provide a system of the type stated which permits the generating of two or more character elements or characters in a single character location on the screen of a moitor.

It is another object of the present invention to provide a system of the type stated which permits an interleaving of graphical symbols to generate a high resolution graphic diagram.

It.is also an object of the present invention to provide 4 a method of generating an alpha-numeric and/ or graphical display on the screen of a monitor. and which enables effective modifying of the characters which form the alphanumeric and/or graphical display.

It is another salient object of the present invention to provide a system of the type stated which is highly efficient and relatively simple in its operation, thereby permitting the use of the system by relatively unskilled personnel.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement and combination of parts presently described and pointed out in the claims.

GENERAL DESCRIPTION .The present invention is highly effective in combining two or more characters in a single character location or raster location for presentation on the screen of a monitor. In accordance with the present invention, it is possible to modify an alpha-numeric character or a graphical character or to otherwise interleave characters. Generally, in most character, generating and display systems, each character will assume one raster location on the screen of a monitor. Thus,in order to form a graphical character, a keyboard mechanism or other form of entry device, as will be hereinafter described, would be actuated in order to form graphical character elements which may be combined in a suitable pattern. In like manner, the entry mechanism could be actuated in .a proper manner in order to generate arabic characters or numeric characters. Again, each particular character thus generated such as an arabic character or a numeric character would lie in an individual raster location unless the operator of the system permitted generation of two or more characters in the same location. 'The graphical characters may be comprised of a series of graphical character elements, all of which may be combinable in a single raster location to form a particular graphic character, in a manner to be hereinafter described. A group. of these graphic characters may also be combined to form a graphic display, also in a manner be hereinafter described.

As indicated previously, the system of the present invention is operable for displaying both arabic and numeric characters, as well as graphical characters. As used herein, the term graphical character represents a character which alone, or in combination with other graphical characters, presents an illustration for visual review, rather than for reading as in the case of alphanumeric text. Accordingly, the term graphic or graphical could represent any type of geometric construction, such as a line, whether it be curved, curvilinear or straight, line segments, points or the like. Generally, a graphic character would represent only a segment of a final display so that if a circle were to be portrayed, a group of these graphic characters, each representing an arc, would be combined in such manner as to form the circle. The term graphic display represents the presentation of graphical characters combined to form a geometric or like pattern as opposed to alpha-numeric text. The term informational display as used herein represents the presentation of either graphical characters and/or alpha-numeric characters alone, or in combination with other forms of information.

In accordance with the present invention, it is now possible to add a modifier to a particular graphical character or alpha-numeric character as described above. The ,term modifier or modifying is used herein in its generic sense to represent either a superimposition or an interleaving of another character or;

the over the letter e in a second raster location irnrnediately following the raster location displaying 6.

, However, in accordance with the present invention, the

operator of the system can also introduce the letter e into one raster location, and in a manner to be hereinafter described generate an accent over the letter a in the same raster location to achieve the symbol e.

In like manner, it is also possible to interleave various graphic symbols or characters in a single raster location in order to provide a high resolution cathode ray tube graphic display. In this case, the operator could generate a series of first row of rectangles or squares in one raster location and where spaces exist between the various rows of squares or rectangles. Immediately following this, the operator can introduce a second set of rows of squares or rectangles in the spaces between the various first rows of squares or rectangles mentioned above.

Thus, one could include a first graphical character in a raster location and add a modifier in the form of another graphical character. In like manner, one could introduce an alpha-numeric character into a raster location and introduce as a modifir therefor, another alpha-numeric character in the same raster location, or

in the alternative, one could introduce an alphanumeric character into a raster location and thereafter introduce a graphical character or other form of mark or designation into the same raster location and this latter mark or designation could constitute a modifier.

The operator of the system of the present invention can introduce more than one character in the same raster location by merely back-spacing after introducing the first character through the keyboard. Thus, in order to introduce the letter e into a raster location, the operator of the system would actuate the letter e on the keyboard of the system. Thereafter, the operator would merely back-space and introduce the accent by means of the keyboard. This will permit both letter e and the accent to appear in the same raster location, causing the two characters to be superimposed. This action is often defined as over-striking. In a conventional CRT raster type operation, it is not possible to overstrike a character due to the fact that there is only one memory location corresponding to each character position. This, in a conventional system if one-attempted to overstrike, the second character entered into this location would automatically erase and replace the first character. However, in accordance with the present invention, dual memories are employed having corresponding pairs of memory locations which, in turn, correspond to raster positions on the monitor so that dual characters may be entered into a particular raster location. Y

In general terms, the present invention can be described as a system for generating the display of characters on the screen of a monitor whichhas a plurality of character locations thereonand for introducing at least two of these characters in one or more of the character locations. This system would generally comprise a first and second storage means, and an. input means for introducing data representing characters from an externalsource and for introducing some of the characters into the first storage means and some of the characters into the second storage means. A character generating means is operatively connected to the first and second storage means. The monitor is again operatively connected to the character generating means for-displaying the characters thus generatedin the character generating means. Finally, location control means are provided for selectively introducing the characters into the proper character locations on the screen of the monitor and enable at least a character from the first storage means and from the secondstorage menas to be included in and displayed in the same character location on the screen of the monitor.

In further detail, the system can be further characterized in that the input means comprise a data entry mechanism and a control means which is operatively interposed between the data entry mechanism and the first and second storage means. This data entry mechanism is preferably, though not necessarily, a manually operable keyboard. However, it should be recognized that other forms of entry means such as computer entry and the like could also be employed. Furthermore, these first and second storage means are generally serially accessible memories.

A selector means is operatively connected to the output of the first and second storage means and is operatively interposed between the first and second storage means and the character generating means and that this character generating means in one embodiment of the invention comprises only a single character generator.

However, in another embodiment of the present invention an individual character generating means is operatively connected to each of the storage means so that a pair of character generators are employed and a combining circuit is operatively connected to the output of each of these individual character generators. In this latter case, the same location control means is operatively associated with both the character generators.

As mentioned above, one character can be placed in one character location on the screen of the monitor under the control of the operator, or a pair of characters can be located in the same character location. In a preferred aspect of the present invention, this character location is a single raster location of the screen of the monitor.

In other general terms, the system of the present invention may be described as comprising an input means for generating a multi-bit binary word representative of each of the characters. This system also includes the first storage means operatively connected to theinput means to store a first of the multi-bit words representing the first character in a character location in said first storage means. In like manner, a second storage means will store a second multi-bit word representing a second character in a corresponding character location, only when the first and second characters are to appear in the same character location on the monitor. This last-named means will store the second multi-bit word in the first storage means if the second character is not to appear in the same character location as the first character. This system, of course, also includes the character generating means operatively connected to the first and second storage means for generating the proper characters from the multi-bit words. The monitor is operatively connected to this character generating means for displaying these characters.

In further detail, this system can be characterized in that the first and second characters are each represented by multi-bit words of the same binary length and this multi-bit word is preferably an eight-bit word.

There are several ways to control the input of the data into either of the first or the second storage means. In one aspect of the present invention, the input means could comprise a means for back-spacing a character to automatically introduce the multi-bit word representing this character into the second storage means. In a second aspect of the present invention, the input means could generate a code for each multi-bit word representing a character which is to be introduced into the second storage means. As a third aspect of the present invention, the input means could comprise a first switch to be actuated for introducing the multi-bit words representing the characters into the first storage means and a second switch to be actuable for introducint the multi-bit words representing the characters to be introduced into the second storage means.

It can be observed that the system of the present invention is highly unique in that it is now therefore possible to add a modifier to a character. In this case, this system will be described as including the first and second storage means mentioned above, and the input means for introducing data from an external source representing a first type of character into the first storage means. This input means would also introduce data 6. from an external source representing the second type of character in the second storage means where the second type of character is capable of modifying the first type of character. The character generating means will be operatively connected to these first and second storage means for generating the character and the modifier therefore. The monitor would operatively be connected to the character generating means for displaying the character and the modifier therefore in the same character location, which is preferably a single raster location.

It could also be observed that the system of the present invention is highly effective for increasing the resolution of a graphical display. In this case, this system would alsocomprise the input means for introducing first data representing graphical character elements which are combinable to represent a graphical character in a raster location on the screen of a monitor. The first storage means is operatively connected to this input means for receiving the data representing the graphicalcharacter elements. The input means is also adapted to introduce second data representing graphical character elements which are also combinable to represent a graphical character in a single raster location on the screen of the monitor. The second storage means is likewise operatively'connected to the input means for receiving the second data representing graphical character elements. The character generating means is operatively connected to the first and second storage means as aforesaid for generating the first graphical character from the first data and a second graphical character'from the second data. Finally, the monitor is operatively connected to the character generating means for receiving each of the graphical characters and displaying each of these graphical characters in the same character location.

This system for increasing the resolution of the graphical display can be further characterized in that the means operatively associated with the character generating means properly locates each of these characters on the screen of the monitor. In a preferred aspect, each of these characters are similar and interleaved in the character location.

The method of the present invention can be described as a method for generating a display of characters on the screen .of a monitor having a plurality of character locations thereon and where two or more characters may be introduced into any one or more of the character locations. This method comprises generating the multi-bit word representative of each character and storing a first multi-bit word representing one first character in a character location of a first storage means. The method includes the storing of a second multi-bit word representing a second character in a corresponding character location in a second storage means only when the first and second characters are to appear in the same character location on the screen of a monitor. However, if the second character is not to appear in the same character location on the screen of the monitor, the second multi-bit word will be stored in the first storage means. The method includes the generating of the proper characters from each of these multibit words and thereafter displaying the characters on the screen of the monitor.

This method for generating the display of characters can be further characterized in that the first and second characters are represented by multi-bit words of the 7 same binary length and preferably, these multi-bit words are eight-bit words. In addition, this method for generating the display can be characterized in that one character location preferably consists of one raster lo cation on the screen'of the monitor. 1

I F IGURES, Having thus described the invention in general terms,

reference will now be made to the accompanying drawings in which:

FIG. 1 is a schematic view of an electrical circuit which permit character generation of the type described, and which has been constructed in accordance with and embodies the present invention; g

FIG. 2 is a schematic view of a modified form of systern which permits character generation of the type described; V

FIGS. 3 is a schematic side elevational view of one front pattern which can be achieved by use of the character generation in accordance with the present invention;

FIG. 4 is a schematic side elevational view of another form of front pattern which can be achieved by using the character generation system of the present inventron; a

FIG. 5 is a schematic side elevational view of stillanother form of front pattern-which can" be achieved by using the character generation system of 'the present invention; and FIG. 6 is a schematic view showing a synchronized two-tier memory which can be utilized in the system of lflGS. 1 and 2 inf-accordance with thepresent inventron.

DETAILED DESCRIPTION Referring now in more detail and by reference characters to the accompanying drawings which illustrate practical embodiments of the present invention, S designates a system which comprises a data entry mecha-' nism 10 which may be in the form of a keyboard or similar mechanism for introducing characters of the type tobe displayed. This data entry mechanism 10, would ters to. be generated. For example, characters can con-v veniently be generated in, for example, the Russion languagewhich requires an additional number of keys and thus, the keyboard would be, provided with the proper number of keys. The keyboard would also be provided with a space bar for the generation of spaces between any of the alpha-numeric characters. This keyboard entry device will also normally include additional keys having punctuation marks, such as periods, commas,

asterisks, or the like, as desired.

A graphic keyboard, preferably in the form of a mimic style key board may also be used to compose acter generating system, a plural point pattern such as a graphic diagram. Thus, in one form of graphic char- 8 a'six-point pattern may begenerated. In like manner, a plural-bar pattern, such as a four-bar pattern may also be generated. The graphic character generating system could also include a combination of the multi-point pattern and the multi-bar pattern. Thus for example, if an eight-dot by a twelve-dot raster locations were to be used for the displaying of these graphic characters, the various dots or bars would be generated in the font in order to produce the desired graphical character.

The graphic patterns which may be introduced by actuation of keys on a keyboard can be formed in any desired pattern 'in order to achieve the desired graphic display. Thus, by actuation of the keys which generate the bar character elements, the operator can generate a series of bars which represent a line. In like manner, by actuating the proper keys on the keyboard, the operator can generate a series of points which form a curve. The various graphicalcharacters can then be suitably placed on the screen in any desired arrangement.

In the system of the present invention, a multi-bit word and preferably an eight-bit data word may be used to represent each character which may be generated including spaces and the like, thus, each numeric character and each arabic character included in the alpha-numeric code, as well as each graphical character would be represented by an eight' bit data word. In both the' graphical andthe alpha-numeric characters, only up to seven of the bits of each eightbit word would be used to describe the character. The eighth bitwhich is generally the most significant bit in each character word is a characterization bit for determining whether the accompanying seven bits represent an alphanumeric character or a graphical character. When utilizing the bar and point pattern for two forms of graphical character elements, four hits may be used to represent four bars andsix bits may be'used to represent six parts. The seventh bit used also constitutes a characterization bit to distinguish between the plural-bar and the plural-point pattern.

The following chart illustrates the eight-bit word construction used for each character word in the present invention. Each character whether a graphical character, an alpha-numeric character including both the first characters and the second characters which may serve as a modifier, willbe formed of an eight-bit word.

Thus, each eight bits represent one word and hence one. character which constitutes one byte in the preferred digital system employed. Notwithstanding, the present invention is operable with other forms of digital codes such asa four-bit BCD code to represent nu meric characters, a five-bit code to represent any arabic or numeric character and that the present invention is not limited to an eight-bit code as employed herein.

Furthermore, a byte could contain less than eight bits and a character word could be comprised of a plurality of bytes so that if a four-bit code were employed, one character word could be represented by two bytes of bit information.

A control circuit 12 is operatively connected to and receives the entered data from the data entry mechanism 10. The function and operation of the control circuit 12 will be more fully discussed hereinafter. Connected to the one output 14 of the control circuit 12 is a first memory unit 16 and similarly connected to a sec ond output 18 of the control circuit 12 is a second memory unit 20. These memory units 16 and 20 are preferably synchronized two-tier memories as more fully illustrated in FIG. 6 of the drawing. Thus, by reference to FIG. 6, it can be observed that each memory section is essentially eight bits wide to accomodate an eight-bit word and the memories are provided with twelve hundred eighty bit locations. Each eight bit word will circulate in the memory in parallel and in synchronism with the raster of the cathode ray tube monitor. Both of the memories will also move in synchronism with each other. The twelve hundred eighty character location thereupon provides for an eighty by sixteen display format when utilizing eight-bit character words. When both of the memories are loaded with eight-bit word information, then character modification can take place in accordance with the present invention, and in a mannerto be hereinafter described in more detail.

In the system S, the first memory 16 provides an output 22 to a selector circuit 24 and the second memory 20 provides an output 26 to the selector curcuit 24. The selector 24, in turn, provides an output to a char acter generator 26, in the manner as illustrated in FIG. 1. The selector circuit 24 is essentially a conventional switching circuit which permits selection between either of the outputs 22 or 26 from the respect memories 16 and 20. In this way, the selector circuit 24 will select the eight-bit character word from either of the memories 16 or 20 for ultimate transmission to the character generator 26. Normally, selection will take place on an alternate basis, that is, the first character word to be transmitted to the generator 26 will be derived from the memory 16, the second character word will be derived from the memory 20, the third character-word will be derived from the memory 16, and so forth.

The character generator 26 will preferably be constructed so that it is capable of generating both of the graphical character and the alpha-numeric characters as aforesaid Generally, the character generator 26 may be in the form of a gating circuit which gates selected bits from the eight-bit words transmitted from the selector 24. This gating will take place under the control of a memory device 28, which in preferably a readonly-memory. The read-only-memory will determine the geometric layout of each character specified by the data which is introduced into the character generator 26 from the selector 24. In this way, any character location in either of the memories 16 or 20 which has data loaded therein will be displayed on the screen of a monitor 30.

The monitor which is utilizedin accordance with the present invention is preferably a display screen operable with a raster pattern, such as a standard television display screen. The screen used for the purposes of describing the present invention will typically contain 32 vertically extending columns which represent a total of 32 raster locations or cells per line and 16 horizontally extending rows which represent a total of 16 lines. Accordingly, a screen of this size would contain 5 l2 raster locations or cells and hence could display a maximum of 512 graphic characters and/or alpha-numeric characters at any point in time. One complete graphic display may or may not use all of the possible 5 l 2 raster or character locations or cells and the complete display at any point in time is referred to in the art as one page.

A screen of the size mentioned above having a five hundred twelve raster locations would permit generation of a page-with a maximum number of 512 character locations. It should be recognized that the screen and, therefore, the page could be composed of any desired number of characters by altering the number of character columns and character rows or lines. Each raster location on the screen which defines one character location has been assigned a size of 12 horizontal dot rows by eight vertical dot columns or a total raster location size of 96 dots. These raster locations will generally have an aspect ratio of three to two inasmuch as many display systems which utilize interactive computer display terminals employ this raster location size. Nevertheless, it should be understood that essentially any size raster location could be employed for the purposes of the present invention.

Generally, the screen of the monitor is provided with a phosphorus coating which is scanned by an electron beam in these raster pattern cathode ray tube devices. Furthermore, a cathode in the tube will emit an electron stream through a grid and this electron stream will be focused on an accelerating anode. A pair of oppositely disposed deflection plates will enable the electron beam to in effect scan or sweep the screen.-

The screen which essentially constitutes one frame is typically scanned in about one-thirtieth of a second, and preferably contains a pair of interlaced fields which form the frame and where each field is scanned in about one-sixtieth'of a second. The beams in the two fields will generally scan from left to right, and will retrace in a substantially shorter period of time than the scan or sweep. The beam will be modulated by the grid and the intensity of the light will be a function of the voltage applied to the grid. Furthermore, the beam will be deflected either electrostatically, though electrostatic defelection is the preferred form.

Returning again to FIG. 1, it can be observed that this system S operates on a so-called field sequential basis of operation producing two or more characters into a particular raster location. The selector circuit 24 will alternately gate the output of each of the memories 16 and 20 into the character generator 26. Thus, on one field, the output of the memory 16 will be introduced into the character generator 26 and on the next field, the output of the memory 20 will be introduced through the selector circuit 24 into the character generator 26. At normal TV rates, a field is typically scanned at sixty times per second and a frame, which in this case, comprises two fields, one from the memory 16 and one from the memory 20, will be scanned thirty times per second. Thus, the character generator 26 will alternately display all of the contents of the memory 16 and then all of the contents of the memory 20. In each case, as the character is introduced into the character generator 26, the read-only-memory 28 will determine the geometric layout of each character as specified by the data. For example, if a character exists in' a particular memory location in the memory 16 and no character exists in a corresponding memory location in the memory 20, the character in the memory 16 will be generated at the character generator 26 and displayed on the screen of the monitor without any modifier therefore or without any the character appearing in the same raster location. If, on the other hand, a character existed in a particular memory location in the memory 16 and a character also existed in the corresponding character location in the memory20, the characters in each'of these corresponding character locations would be alternately generated by the character generator 26 and therefore appear superimposed one upon the other at the same raster location on the screen of the monitor The control circuit 12 can control the entry of the data into the two memories 16 and 20 in several ways depending on the particular application of the system of the present invention. In one particular aspect, the control circuit 12 will automatically enter data into the memory 16 until receipt ofa back-space command which can be generated at the keyboard or data entry device 10. In this respect, the backspace command would also constitute a form of coded character. When a back-space command is received, it will backspace the cursor at the monitor and enter the next character into the memory-'20; Automatically thereafter, the cursor will be advanced and enter the following data into the memory 16 until such time as another backspace command is received.

In another way, the control circuit 12 can recognize enter allsubsequent data into the memory 20 until re-v ceipt of a shift-in command and in this case all of the subsequent data would be transferred to the memory 16. Implementation of any'of these techniques for entering the data into the pair of memories 16 and 20 can be accomplished under hardwired circuitry or under the control of the local processor. The control circuit 12 is not described in any further detail herein, since the inputoutput relationships described above are readily determinable by the skilled artisan can be altered in order to obtain the desired control action.

FIG. 2 of the present invention illustrates modified form of system S' which can be utilized for entering two or more characters in the same raster location on the screen of a monitor, or for otherwise modifying a character in a particular raster location. The system S also comprises a data entry mechanism 32 which is substantially identical to the data entry mechanism 10 and would preferably exist in the form of a keyboard. The output of the data entry mechanism 32 is also introduced into a control circuit 34 which in this case, would be substantially similar to the control circuit 12. Furthermore, and in like manner, the control circuit 34 12 is provided with outputs 36 and 38 which are respectively introduced into memories 40 and 42, the latter corresponding essentially to the memories 16 and 20 respectively. Thus, the memories 40 and 42 would have the same type of memory location structure as illustrated in FIG. 6 of the drawings.

The memory 40 is provided with an output line 44 for introducing the contents of the memory 40 into a character generator 46 and the memory 42 is similarly provided with anoutput 48 for introducing the contents in the memory 42 into a second character generator 50. The character generators 46 and 50 are operable under the control of read-only-memory units 52 and 54 rethe location of character generated in this generator 50. Nevertheless,'the operation of producing two or morecharacters in a particular raster location or for otherwise. modifying a character in a raster location is substantially similar. In this case, if a character was generated in the character generator 46 at a particular location, and another character was generated in a corresponding character location in the character generator 50, these two characters would be introduced into the same raster location on the screen of the monitor.

The outputs of the two character generators 46 and 50 are introduced into a combining circuit 56 for com bining the two characters in the manner as aforesaid and the output of this circuit 56 is then introduced into a monitor 58 which is substantially identical to the monitor 30.

It can be observed that the system S, shown in FIG. 2, operates on the so-called line sequential basis of operation for introducing two or more characters into the same location or for modifying a character in a raster location. In this case, it can also be observed that the field and frame repetition rates are identical because in this case each field in the particular frame is the same by virtue of using a pair of character generators and a pair of read-only-memories associated with these character generators.

In operation, if the operator of the system desired to introduce a pair of characters into a particular raster location on the screen of the monitor, the operator would merely actuate the proper key in order to generate the first character.'Thereafter, by use of the proper coding system described above, the operator could introduce the second character into a corresponding memory location into the second memory. Either the system S or the system S will thereupon display both characters simultaneously into the same raster location. Consequently, it can be observed that the system of the present invention is highly effective in introducing a modifier into the same character location as a particular character, or otherwise interleaving, that is superimposing a pair of characters into the same location.

In each case, when the operator of the system actuates a key, the system will generate an eight-bit word corresponding to the character represented by that key. Thus, an eight-bit word will be generated for each graphical character and each alpha numeric character. In like manner, an eight bit data word will be generated for each other character including spaces and the like which can be generated by the entry device. It should also be understood that the same eight bit data word form will be generated for every character, whether that character is to be stored into the first of the memories or the second of the memories.

FIG. 3 illustrates one form overstriking with two sixpoint patterns as graphical characters. In this case, to represents one font pattern or raster location on the screen of the monitorand it can be observed that a sixpoint pattern in the form of a first character designated by the shaded areas 62 is introduced into the raster location. A second six-point pattern designated by the solid areas 64 is also introduced into the same raster lo cation. Thus, it can be observed that one of the sixpoint patterns 64, and in this case would effectively enable a 160 by 96 graphic dot matrix to be used for constructing a continuous diagram.

A four-bar pattern mentioned above can also be modified in the manner as illustrated in FIG. 4. Reference numeral 66 represents a similar font pattern with a four-bar graphical character 68 designated by the shaded lines located in the raster location. Another form of four-bar character 70 designated by the solid lines in FIG. 4 is also superimposed with respect to the first four-bar characters 68. Finally, FIG. 5 illustrates yet another form of superimposing or otherwise interleaving pairs of characters. In the case of FIG. 4, it can be seen that a compound mathematical symbol can be constructed as illustrated, whereas in F IG, 5, a particular arabic character is accented. It can be observed that the arabic characterdesignated by reference numeral 72 in the solid block lines is generated as one form of character and an accent 74 designated by the shaded lines represents another form of character.

It should be understood that the system of the present invention is not limited to the display of only two characters in particular raster location. The system could be modified by including more than two memory units and by expanding the control circuit in order to display three or more characters in a particular character location. In this case, additional read-only-memory control units would probably be employed in order to properly position each of the characters in the raster location.

It can be seen that the display system of the present invention is highly effective with standard display monitors using a raster pattern, and particularly with television monitors for displaying both alpha-numeric and graphical characters in order to generate a complete informational display. The system of the present invention is highly effective in that it is capable of accepting ASCII coded alpha-numeric data for display on one or more television monitors and in addition, video-signal produced by the system of the present invention is compatible with substantially any commercially available television monitor. Furthermore, it is possible to write, through actuation of the keyboard, or other data entry device and to access and record this information into the computer storage. The generated graphical characters are formed by plural-point or plural-bar font patterns and the nature of these displays lends to easy viewability. Moreover, the system of the present invention is very convenient to author and present conceptual information for construction purposes.

The components in the system of the present invention have been uniquely selected so that the graphic characters generated by the system S would be displayed along with the standard alpha-numeric data and further, the graphical information uses a data format which is completely compatible with the data format of alpha-numeric information. In addition, the same storage medium which is used for the retention of alphanumeric data is also used for the retention of the data representing graphic characters. Thus, the data for the graphical characters could be randomly stored in a computer memory along with the alpha-numeric data or separated therefrom. The exact addressing scheme used in the computer is not part of the present invention since the systems of the present invention are peripheral thereto, as stated above. However, one effective form of recording a page containing alpha-numeric characters and graphical characters employs a modified form of associative addressing where the data representing the graphical characters can be stored in positions related to the storage positions of the alphanumeric data.

There are many auxiliary components which can be used with the system of the present invention and many substitutes of components which can be made. For example, a video-signal generator could be used for converting the generated characters and a television input into a composite video-signal and for also providing timing and synchronizing pulses. Furthermore, either fast or slow memory organizations may be employed depending on the requirements of the user of this system. v

The system of the present invention may also be provided with an optional protection control for displaying fields of fixed data and fields of variable data. In this control system memory locations allocated to fixed data are placed in a protect" condition to prevent the fixed data from being erased or read out and to enable the operator to erase only the variable data. A protection control is provided for permitting the operator to hold the data constant in the protection fields while varying the data in the non-protected fields. When the protection control is off, all character locations will be unprotected and the data may be entered or altered in any location. When the protection control is switched on, the data in the assignedlocations will thereafter become protected. The fields assigned to the protected variable data may be of any length. Furthermore, this protection control system could be constructed in such manner that the protected characters written into the memories will be displayed at half of normal intensity.

Thus, there has been illustrated and described a unique and novel system and method for introducing two or more characters from the same character location into a particular raster location on the screen of a monitor and whichfulfills all the objects and advantages sought therefor. It should be understood that the system of the present invention is not limited to the exact configuration illustrated and described and that many changes, modifications, variations and other uses and applications of this system will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings. All

such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered acters in one or more of said character locations, said system comprising first and second storage means, input means for introducing data representing characters from an external source and for introducing some of said characters into said first storage means and some of said characters into said second storage means, character generating means operatively connected to said first and second storage means for selectively receiving characters from said. first and second storage means, said monitor being operatively connected'to said character generating means for displaying the characters thus generated in said character generating means, and location control means for selectively intro ducingcharacters into proper character locations on the screen of said monitor and to enable at least a character from said first-storage means and a character from said second storage means to be included in and displayed in the same character location on the screen of the monitor. I

-2. The system for generating a display of characters of claim 1 further characterized in that said input means comprises a data entry mechanism and a control means operatively interposed between said data entry means and said first and second storage means. 3. The system for generating a display of characters of claim 2 further characterized in that said data'entry mechanism is a manually operable keyboard.

4. The system for generating a display of characters of claim 1 further characterized in that said first and second storage means are serially or randomly accessi- 6. The system for generating a display of characters of claim 1 further characterized in that an individual character generator is operatively connected to each .said' storage means and a combining circuit is operatively connected to each said individual character generator.

7. The system for generating a display of characters of claim 6 further characterized in that a separate location control means is operatively associated with each character generator.

8. The system for generating a display of characters of claim 1 further characterized in that one character location consists of one raster location on the monitor which is operable with a TV-type raster pattern.

9. A system for generating a display of characters on the screen of a monitor and for modifying the characters thereon, said system comprising first and second storage means, input means for introducing data from an external source representing a first type of character into said first storage means and data also from an external source representing a second type of character into said second storage means, and where said second type of character is capable of modifying said first type of character, character generating means operatively connected to said first and second storage means for generating the character for display from said first storage means and for generating any modifier therefor from said second storage means, said monitor being operatively connected to said character generating means for displaying the character thus generated and displays the modifier therefor in the same character location.

10. The system for generating a display of characters of claim 9 further characterized in that a location control means is operatively connected to said character generating means to control the location of the characterand modifier therefor in the same character location on the screen of the monitor.

11. The system for generating a display of characters of claim 10 further characterized in that said first type of characters are different than said second type of v characters. I

12. A system for generating a display of characters in the screen of a monitor having a plurality of character locations thereon and where two or more characters may be introduced in any one or more of said character locations, said systems comprising input means for generating a multi-bit word representative of each character, a first storage means and a second storage means, means operatively connected to said first and second storage means and said input means to store a first multi-bit word representing one first character in a character location in said first storage means and for storing a second multi-bit word representing a second character in a corresponding character location in said second storage means only when said first and second characters are to appear in the same character location on said monitor, said last named means storing said second they become superimposed.

multi-bit word in said first storage means if said second character does not appear in the same character location as said first character, character generating means operatively connected to said first and second storage means for generating the proper characters from said multi-bit words, and said monitor being operatively connected to said character generaing means for displaying said characters. i

13. The system for generating a display of characters of claim 12 further characterized in that said first and second characters are represented by multi-bit words of the same binary length.

14. The system for generating a display of characters of claim 13 further characterized in that said multi-bit words are eight-bit words.

15. The system for generating a display of characters of claim 12 further characterized in that said input means comprises means for overstriking onecharacter upon another by entering the first character into first storage meansthen back-spacing then entering the second character into the second storage means.

16. The system for generating a display of characters of claim 12 further characyerized in that said input automatically enters a character into one memory or the other as a function of its coding and automatically enters the characters in corresponding locations so that 17. The system for generating a display of characters of claim 12 further characterized in that said input means comprises a first switch means to be actuated for into said first storage means and a second switch means to be actuable for introducing multi-bit words representing characters into said second storage means.

18. A method for generating a display of characters on the screen of a monitor having a plurality of character locations thereon and where two or more characters may be introduced in any one or more of said character locations, said method comprising generating a multibit word representative of each character, storing a first multi-bit word representing one first character in a character location of a first storage means and storing a second multi-bit wordrepresenting a second character in a corresponding character location in a second storage means only when said first and second characters are to appear in the same character location on said monitor, storing said second multi-bit word in said first storage means if said second character is not to appear in the same character location as said first character, generating the proper characters from said multibit words, and displaying said characters on the .screen of said monitor.

19. The method of generating a display of characters of claim 18 further characterized in that said first and second characters are represented by multi-bit words of the same binary length.

20. The method of generating a display of characters of claim 19 further characterized in that said multi-bit words are eight-bit words.

21. The method for generating a display of-characters on the screen of a monitor of claim I8 further characterized in that one character location consists of one raster location. 7 I

22. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said second character is a modifier for said first character.

23. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises back-spacing a character to automatically enter a character into the second storage means.

24. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises recognizing the code for each multi-bit word representing a character and entering it into a pre-determined memory.

25. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises actuating a first switch means for introducing multi-bit words representing characters into the first storage means and actuating a second switch means for introducing multi-bit words representing characters into the second storage means.

26. A system for increasing the resolution of a graphical display, said system comprising input'means for introducing first data representing graphical character elementscombinableto represent a graphical character in a character location on the screen of a monitor, first storage means operatively connected to said input means for receiving the data representing the graphical character elements, said input means also being adapted to introduce second data representing graphical character elements combinable to represent a graphical character in a single character location on the screen of a monitor, second storage means operatively connected to said input means for receiving the second data representinggraphical character elements, character generator means operatively connected to said first and second storage means for generating a first graphical character from the first data and a second graphical character from the second data, and a monitor operatively connected to said character gener ator means for receiving each of said characters and to display each of said graphical character location. I

27. The system for increasing the resolution of a graphical display of claim 26 further characterized in that means is operatively associated with said character generating means to properly locate each of said characters on the screen of said monitor.

28. The system for increasing the resolution of a graphical display of claim 27 further characterized in that'each said characters are similar and are interleaved in said character location.

29. The system for increasing the resolution of a graphical display of claim 28 further characterized in that said character location is a single raster location.

30. A method for increasing the resolution of a graphical display, said method comprising introducing first data representing graphical character elements combinable to represent a graphical character in a raster location on the screen of a monitor, introducing the data representing the graphical character elements into a first storage means, introducing second data representing graphical character elements combinable to represent a graphical character in a single raster localocation on the screen of a monitor.

characters in the same 

1. A system for generating a display of characters on the screen of a monitor having a plurality of character locations thereon and for introducing at least two characters in one or more of said character locations, said system comprising first and second storage means, input means for introducing data representing characters from an external source and for introducing some of said characters into said first storage means and some of said characters into said second storage means, character generating means operatively connected to said first and second storage means for selectively receiving characters from said first and second storage means, said monitor being operatively connected to said character generating means for displaying the characters thus generated in said character generating means, and location control means for selectively introducing characters into proper character locations on the screen of said monitor and to enable at least a character from said first storage means and a character from said second storage means to be included in and displayed in the same character location on the screen of the monitor.
 2. The system for generating a display of characters of claim 1 further characterized in that said input means comprises a data entry mechanism and a control means operatively interposed between said data entry means and said first and second storage means.
 3. The system for generating a display of characters of claim 2 further characterized in that said data entry mechanism is a manually operable keyboard.
 4. The system for generating a display of characters of claim 1 further characterized in that said first and second storage means are serially or randomly accessible memories.
 5. The system for generating a display of characters of claim 1 further characterized in that selector means is operatively connected to the output of said first and second storage means and is operating interposed between said first and second storage and said character generating means, and that said character generating means comprises a single character generator.
 6. The system for generating a display of characters of claim 1 further characterized in that an individual character generator is operatively connected to each said storage means and a combining circuit is operatively connected to each said individual character generator.
 7. The system for generating a display of characters of claim 6 further characterized in that a separate location control means is operatively associated with each character generator.
 8. The system for generating a display of characters of claim 1 further characterized in that one character location consists of one raster location on the monitor which is operable with a TV-type raster pattern.
 9. A system for generating a display of characters on the screen of a monitor and for modifying the characters thereon, said system comprising first and second storage means, input means for introducing data from an external source representing a first type of character into said first storage means and data also from an external source representing a second type of character into said second storage means, and where said second type of character is capable of modifying said first type of character, character generating means operatively connected to said first and second storage means for generating the character for display from said first storage means and for generating any modifier therefor from said second storage means, said monitor being operatively connected to said character generating means for displaying the character thus generated and displays the modifier therefor in the same character location.
 10. The system for generating a display of characters of claim 9 further characterized in that a location control means is operatively connected to said character generating means to control the location of the character and modifier therefor in the same character location on the screen of the monitor.
 11. The system for generating a display of characters of claim 10 further characterized in that said first type of characters are different than said second type of characters.
 12. A system for generating a display of characters in the screen of a monitor having a plurality of character locations thereon and where two or more characters may be introduced in any one or more of said character locations, said systems comprising input means for generating a multi-bit word representative of each character, a first storage means and a second storage means, means operatively connected to said first and second storage means and said input means to store a first multi-bit word representing one first character in a character location in said first storage means and for storing a second multi-bit word representing a second character in a corresponding character location in said second storage means only when said first and second characters are to appear in the same character location on said monitor, said last named means storing said second multi-bit word in said first storage means if said second character does not appear in the same character location as said first character, character generating means operatively connected to said first and second storage means for generating the proper characters from said multi-bit words, and said monitor being operatively connected to said character generaing means for displaying said characters.
 13. The system for generating a display of characters of claim 12 further characterized in that said first and second characters are represented by multi-bit words of the same binary length.
 14. The system for generating a display of characters of claim 13 further characTerized in that said multi-bit words are eight-bit words.
 15. The system for generating a display of characters of claim 12 further characterized in that said input means comprises means for overstriking one character upon another by entering the first character into first storage means then back-spacing then entering the second character into the second storage means.
 16. The system for generating a display of characters of claim 12 further characyerized in that said input automatically enters a character into one memory or the other as a function of its coding and automatically enters the characters in corresponding locations so that they become superimposed.
 17. The system for generating a display of characters of claim 12 further characterized in that said input means comprises a first switch means to be actuated for introducing multi-bit words representing characters into said first storage means and a second switch means to be actuable for introducing multi-bit words representing characters into said second storage means.
 18. A method for generating a display of characters on the screen of a monitor having a plurality of character locations thereon and where two or more characters may be introduced in any one or more of said character locations, said method comprising generating a multi-bit word representative of each character, storing a first multi-bit word representing one first character in a character location of a first storage means and storing a second multi-bit word representing a second character in a corresponding character location in a second storage means only when said first and second characters are to appear in the same character location on said monitor, storing said second multi-bit word in said first storage means if said second character is not to appear in the same character location as said first character, generating the proper characters from said multi-bit words, and displaying said characters on the screen of said monitor.
 19. The method of generating a display of characters of claim 18 further characterized in that said first and second characters are represented by multi-bit words of the same binary length.
 20. The method of generating a display of characters of claim 19 further characterized in that said multi-bit words are eight-bit words.
 21. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that one character location consists of one raster location.
 22. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said second character is a modifier for said first character.
 23. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises back-spacing a character to automatically enter a character into the second storage means.
 24. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises recognizing the code for each multi-bit word representing a character and entering it into a pre-determined memory.
 25. The method for generating a display of characters on the screen of a monitor of claim 18 further characterized in that said method comprises actuating a first switch means for introducing multi-bit words representing characters into the first storage means and actuating a second switch means for introducing multi-bit words representing characters into the second storage means.
 26. A system for increasing the resolution of a graphical display, said system comprising input means for introducing first data representing graphical character elements combinable to represent a graphical character in a character location on the screen of a monitor, first storage means operatively connected to said input means for receiving the data representing the graphical character elements, said input means also being adapted to introduce second dAta representing graphical character elements combinable to represent a graphical character in a single character location on the screen of a monitor, second storage means operatively connected to said input means for receiving the second data representing graphical character elements, character generator means operatively connected to said first and second storage means for generating a first graphical character from the first data and a second graphical character from the second data, and a monitor operatively connected to said character generator means for receiving each of said characters and to display each of said graphical characters in the same character location.
 27. The system for increasing the resolution of a graphical display of claim 26 further characterized in that means is operatively associated with said character generating means to properly locate each of said characters on the screen of said monitor.
 28. The system for increasing the resolution of a graphical display of claim 27 further characterized in that each said characters are similar and are interleaved in said character location.
 29. The system for increasing the resolution of a graphical display of claim 28 further characterized in that said character location is a single raster location.
 30. A method for increasing the resolution of a graphical display, said method comprising introducing first data representing graphical character elements combinable to represent a graphical character in a raster location on the screen of a monitor, introducing the data representing the graphical character elements into a first storage means, introducing second data representing graphical character elements combinable to represent a graphical character in a single raster location on the screen of a monitor, introducing the second data representing graphical character elements into a second storage means, periodically transferring the contents of each said storage means to a character generator means for generating a first graphical character from the first data and a second graphical character from the second data, and simultaneously displaying each of said graphical characters in the same character location on the screen of a monitor. 